The objective of this proposal is to design, develop, and validate a commercially viable human-use smart 128-channel macro & micro ECoG microsystem with integrated recording, stimulation, and impedance measuring capabilities for epilepsy monitoring. The microsystem comprises of a state-of-art microelectronic signal processing component linked to a macro & micro integrated ECoG grid via a thin, highly flexible, bio- compatible micro-ribbon cable on one end and a single percutaneous flexible-cable (pigtail) on the other end. The custom multiplexing ASIC electronics is capable of 128-channel recordings at 16-bit resolution and has fast settle capability (for stimulation option) and patient safety circuitry. The component is contained on a printed circuit board and is encapsulated with Parylene-C and Silicone. The encapsulated microelectronic component unit is encased in a titanium case and resides subcutaneously between the skin and the skull. The integrated microsystem would have unique snow-flake shape grid design containing alternate rows of macro and micro channels. The phase-I would target a short-term goal of developing, bench testing and validating in adult sheep model the complete implantable ECoG microsystem that can be translated to research and clinical lab in the shortest time frame.